This invention relates to Marine and Offshore Industries and more particularly to berthing ships offshore to the floating terminals with the goal of transshipping cargo between two ships.
The economical advantage of utilization Very Large Ships (VLS) for transporting mass bulk cargo and limitations of the existing shallow water ports to handle them created need for the Offshore Deepwater Floating Transshipment Terminals.
Presently, in cases of shallow water import ports, the VLS, before entering port, are partially unloaded "lightened" in deep waters by small shuttle ships until their draft is reduced to the level permitting them to enter the port. In cases of shallow water export ports, the VLS are loaded only partially in the port and after they reach natural deep waters they are loaded to their full draft "topping-off" by small shuttle ships.
One of the drawbacks of these offshore operations is increase in the possibilities of collision between shuttle ship and VLS, since berthing operation often will be performed during the high seas.
Besides the "lightening" and "topping-off" operations, there are often the needs to fully unload (load) VLS outside the shallow water port, because it does not fit into port due to its excessive length even when its draft is reduced.
The existing practice of preventing ships from damaging each other during the berthing operation utilizes floating breasting fenders (pneumatic or rubber). The largest floating breasting dolphins are 15' in diameter and about 20' long and weighting about 20 ton. The maximum deflection of these fenders is about 9' and energy absorption is limited to about 5,000 ft-kips or 700 ton-m.
In spite the giant dimensions of these fenders the berthing VLS practically have to come to a full stop before coming in contact with the fenders. Because of this the safety of berthing operations crucially depends of the weather conditions, thus limiting utilization of the offshore transshipment terminal to a relatively calm seas.